Presentation
Back pain since about 3 months. Left side flank and testicular pain since about 3 weeks. Night sweats, malaise, and weight loss. Left side hydronephrosis on abdominal sonography.
Patient Data
A dual contrast injection protocol was used, with first contrast injection 5 minutes prior to the CT, followed by a second injection with acquisition of late arterial and venous phase scans. There is an ill-defined retroperitoneal soft tissue mass encasing the infrarenal aorta, the inferior mesenteric artery, the left testicular vein, the left ureter, the proximal left iliac vessels, as well as partially the inferior vena cava and the proximal right side iliac vessels. The aorta is not displaced. Mild left side hydronephrosis with delayed contrast excretion by the left kidney. No discrete adenopathy.
Case Discussion
This is a typical case of retroperitoneal fibrosis. The main differential would be retroperitoneal lymphoma, which however would typically demonstrate mass effect and displace the aorta medially and the ureters laterally, not pulling them in medially like retroperitoneal fibrosis frequently does.
Biopsy and subsequent histopathology demonstrated "lymphoplasmatic and hystiocytic infiltration consistent with idiopathic retroperitoneal fibrosis (Ormond disease), not IgG4 positive, with numerous CD68 histiocytes; MDM2 negative ruling out liposarcoma, AE1/AE3 and CK7 negative ruling out other carcinoma".
The patient received an ureteral stent and got systemic steroid therapy for 5 months, after which it was switched to mycophenolate mofetil.
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